JP2024007913A - hub unit bearing - Google Patents

Abstract

To provide a hub unit bearing for enabling appropriate injection molding of a cap.SOLUTION: The cap includes a synthetic resin cap body, and a metal core grid fixed to the cap body, the cap body being wholly bottomed cylindrical and having an approximately disc-shaped resin bottom plate part, and an approximately cylindrical resin cylinder part extending from the radial outside of the resin bottom plate part to the outboard side, the resin cylinder part covering the core grid from the radial outside. On the inner peripheral face of the resin cylinder part, a protruded part protruded to the radial inside is provided on an area at the outboard side or the inboard side further than the core grid.SELECTED DRAWING: Figure 2

Description

The present invention relates to a hub unit bearing used to rotatably support the wheels of an automobile relative to a suspension system.

A rotation speed sensor that combines a hub unit bearing that rotatably supports the wheels (driven wheels) of an automobile relative to a suspension system with a rotation speed detection device that detects the rotation speed of the wheels necessary for controlling ABS, etc. Hub unit bearings equipped with detection devices have been widely used.

For example, Patent Document 1 discloses a bearing for a hub unit bearing that includes a bottomed cylindrical cap body made by injection molding of synthetic resin and a core metal integrally molded in the opening of the cap body. The cap is exposed. In the bearing cap of Patent Document 1, the radially outer side of the core metal is covered with resin, and this resin portion is used as a fitting surface with the inner circumferential surface of the outer ring.

In insert molding, which produces a molded product in which the core metal and resin are integrated, it is difficult to perform injection molding with the core metal insert floating out of the mold, so One of these must be the surface that engages with the mold (the surface that is not covered by the resin). In the bearing cap of Patent Document 1, the inner circumferential surface of the core metal serves as a locking surface with the mold, and is therefore not covered with resin except for the portion where flash (burrs, resin flows out) occurs.

Incidentally, injection molds for axial draw molding include a movable mold located on the radially inner side of the molded product and a fixed mold located on the radial outside of the molded product. The fixed mold is equipped with a gate, and when the mold is opened, the molded product is locked to the movable mold (the locking force is the circumferential stress generated by molding shrinkage of the molten resin) and then removed from the fixed mold. , it is also removed from the movable mold by being pushed by the ejector pin.

In the case of the bearing cap of Patent Document 1, there is almost no resin exposed on the inside in the radial direction, and the core metal supports the circumferential stress generated by molding shrinkage of the molten resin, so it is difficult to remove the molded product from the fixed mold. It becomes difficult. Furthermore, since the sensor insertion hole has a bottom, it is necessary to mold the sensor insertion hole with a fixed mold, and molding shrinkage in this part makes it more difficult to take out the molded product from the fixed mold.

JP 2021-131150 Publication

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a hub unit bearing whose cap can be appropriately injection molded.

The above object of the present invention is achieved by the following configuration.
(1) An outer ring having a double-row outer ring raceway surface formed on the inner peripheral surface;
an inner ring having a double-row inner ring raceway surface formed on its outer circumferential surface;
a plurality of rolling elements rotatably disposed between the double-row inner ring raceway surface and the double-row outer ring raceway surface;
a cap fixed to an inboard side end of the outer ring and closing an opening on the inboard side of the outer ring;
A hub unit bearing comprising:
The cap has a synthetic resin cap body and a metal core fixed to the cap body,
The cap body has a cylindrical shape with a bottom as a whole, and includes a substantially disk-shaped resin bottom plate portion and a substantially cylindrical resin tube portion extending from a radially outer side of the resin bottom plate portion toward the outboard side. death,
The resin cylinder portion covers the core metal from the outside in the radial direction,
In the hub unit bearing, a convex portion protruding radially inward is provided on an inner circumferential surface of the resin cylindrical portion at a portion on an outboard side or an inboard side with respect to the core metal.

According to the hub unit bearing of the present invention, it is possible to provide a hub unit bearing whose cap can be properly injection molded.

FIG. 3 is a cross-sectional view of the hub unit bearing according to the first embodiment. FIG. 2 is an enlarged view of main parts of the hub unit bearing according to the first embodiment. FIG. 7 is an enlarged view of a main part of a hub unit bearing according to a second embodiment. FIG. 7 is an enlarged view of main parts of a hub unit bearing according to a third embodiment. FIG. 7 is an enlarged view of a main part of a hub unit bearing according to a fourth embodiment. FIG. 7 is an enlarged view of main parts of a hub unit bearing according to a fifth embodiment.

[First embodiment]
A hub unit bearing according to a first embodiment of the present invention will be described in detail using FIGS. 1 and 2. FIG. 1 is a sectional view of a hub unit bearing according to a first embodiment. FIG. 2 is an enlarged view of essential parts of the hub unit bearing according to the first embodiment.

Regarding the hub unit bearing, throughout this specification and claims, "outside" with respect to the axial direction refers to the left side in FIG. Also called the "outboard side." On the other hand, the right side in FIG. 1, which is the center side in the width direction of the vehicle body, is referred to as the "inside" in the axial direction, and is also referred to as the "inboard side."

The hub unit bearing 1 of this embodiment is for a driven wheel, and mainly includes an outer ring 2, an inner ring 3, and a plurality of rolling elements 4, 4.

The outer ring 2 has a stationary side flange 7 on its outer peripheral surface, and double-row (two rows) outer ring raceway surfaces 8a and 8b on its inner peripheral surface. During use, the outer ring 2 does not rotate while being supported by the suspension by fixing the stationary side flange 7 to the knuckle of the suspension.

The inner ring 3 includes a hub ring 9 and an inner ring member 10, and is arranged radially inside the outer ring 2 and coaxially with the outer ring 2.

The hub ring 9 has a portion that protrudes axially outward from the axially outer (outboard side) opening of the outer ring 2, and extends radially outwardly so as to rotate the wheel (drive wheel), disc rotor, etc. for braking. A circular ring-shaped rotating side flange 11 is provided for supporting and fixing the member. Specifically, the rotation side flange 11 is provided with a plurality of insertion holes 11a, and a hub bolt 17 is fitted into each insertion hole 11a through serrations. Note that by making the plurality of insertion holes 11a of the rotating side flange 11 female threaded holes and screwing hub bolts into them, it is also possible to support and fix rotating members for braking such as wheels (driving wheels) and disc rotors.

Further, on the outer circumferential surface of the hub ring 9, the inner ring raceway surface 12a of the outboard side row (one row) is located at the portion facing the outer ring raceway surface 8a of the axially outer (outboard side) row of the outer ring 2. It is provided. Further, a small-diameter stepped portion 13 is provided at an axially inner end portion of the outer circumferential surface of the hub ring 9 that faces the outer ring raceway surface 8b of the axially inner (inboard side) row of the outer ring 2.

The inner ring raceway surface 12b of the inboard side row (the other row) is provided on the outer peripheral surface of the inner ring member 10. The inner ring member 10 is externally fitted onto the outer peripheral surface of the small diameter stepped portion 13 of the hub ring 9 with its outboard side end surface abutting against the stepped surface of the small diameter stepped portion 13, and its inboard side end surface is crimped. It is fixed to the hub wheel 9 by being connected and fixed by the portion 24 .

The rolling elements 4, 4 have a pair of rolling elements located between the outer raceway surface 8a and the inner raceway surface 12a of the outboard row and between the outer raceway surface 8b and the inner raceway surface 12b of the inboard row. It is provided so as to be freely rotatable while being held by retainers 6, 6.

A seal ring 5 is supported and fixed on the outboard side end of the inner circumferential surface of the outer ring 2 . The seal ring 5 closes an opening on the outboard side of an internal space 18, which exists between the inner circumferential surface of the outer ring 2 and the outer circumferential surface of the hub ring 9, and in which a plurality of rolling elements 4, 4 are provided. The seal ring 5 is in sliding contact with a large-diameter stepped portion 20 on the outboard side of the inner raceway surface 12a of the outer peripheral surface of the hub ring 9.

An annular encoder 14 is supported and fixed at the inboard end of the inner ring member 10. The encoder 14 includes a support ring 26 and an encoder body 27. The support ring 26 is formed into an L-shaped cross section and an annular shape as a whole by pressing a magnetic metal plate such as a ferritic stainless steel plate such as SUS430 or a rolled steel plate such as SPCC. An outboard side portion of the support ring 26 is externally fitted and fixed to the inner ring member 10. The support ring 26 has a substantially L-shaped cross section and includes an annular annular portion 26a fixed to the inner ring member 10 and a flange portion 26b extending radially inward from the inboard side end of the annular portion 26a. be. The encoder main body 27 is made entirely of a permanent magnet made by mixing a magnetic material such as ferrite powder into rubber or thermoplastic resin, and is formed into a circular ring shape, and is attached and fixed to the inboard side surface of the flange portion 26b of the support ring 26. has been done. On the inboard side surface (detection surface) of the encoder main body 27, S poles and N poles are magnetized alternately and at equal pitches in the circumferential direction.

A bottomed cylindrical cap 30 is fixed to the inboard end of the outer ring 2 to close the opening of the outer ring 2 on the inboard side.

As shown in FIG. 2, the cap 30 includes a cap body 50 made of synthetic resin containing a filler, and a metal core 40 fixed to the cap body 50.

The cap body 50 is made entirely into a bottomed cylindrical shape by injection molding (axial draw molding) synthetic resin, and includes a substantially disk-shaped resin bottom plate portion 51 and a radially outer side of the resin bottom plate portion 51. It has a substantially cylindrical resin cylinder part 53 extending from the part to the outboard side. The resin bottom plate portion 51 is a bottom portion that closes an opening facing inward in the axial direction of the resin cylinder portion 53.

A thick wall portion 52 having a thicker wall in the axial direction than other portions (bulging toward both sides in the axial direction) is provided at a position deviated outward in the radial direction from the center axis of the resin bottom plate portion 51. It is being

The thick wall portion 52 is provided with an insertion hole 54 that passes through the thick wall portion 52 in the axial direction at a portion that faces the detection surface of the encoder main body 27 in the axial direction. The insertion hole 54 is for inserting a sensor (not shown), and the inner peripheral surface of the insertion hole 54 has an inner diameter slightly larger than the outer diameter of the sensor.

An insert nut 56 is molded and fixed to the radially inner portion of the thick portion 52 . The insert nut 56 is a through nut having a female thread formed on its inner circumferential surface and a through hole extending in the axial direction, or a cylindrical cap nut with a bottom provided at the outboard end. Then, with the sensor inserted into the insertion hole 54, a bolt (not shown) that passes through a fixing hole provided in the flange of the sensor is screwed into the insert nut 56, so that the sensor is inserted into the insertion hole 54. Fixed.

The synthetic resin material constituting the cap body 50 is, for example, polyamide 66 resin to which a filler is added. As the filler, for example, glass fiber, carbon fiber, or metal fiber is used as a fibrous reinforcing material. If necessary, amorphous aromatic polyamide resin (modified polyamide 6T/6I), low water absorption aliphatic polyamide resin (polyamide 11 resin, polyamide 12 resin, polyamide 610 resin, polyamide 612 resin) may be added to the polyamide resin. Water resistance may be further improved by adding it as appropriate.

The core metal 40 is made of a metal such as a stainless steel plate or a rolled steel plate, and has an annular shape as a whole. The core metal 40 has an L-shaped cross section and includes a substantially cylindrical core tube portion 41 extending in the axial direction, and a core metal flange portion 43 extending radially outward from the inboard side end of the core metal tube portion 41. It is. The inboard side end portion of the core metal cylinder portion 41 is located on the inboard side rather than the outer ring 2. A cored metal flange portion 43 extending radially from the inboard side end of the cored metal cylinder portion 41 faces the inboard side end surface of the outer ring 2 in the axial direction.

The core metal 40 is molded and fixed to the resin cylindrical portion 53 of the cap body 50. Thereby, the core metal 40 is covered with the resin cylinder part 53 from the outside in the radial direction. In addition, since it is difficult to perform injection molding with the core bar 40 floating from the mold, either the outer diameter side or the inner diameter side of the core bar 40 is a surface that engages with the mold (a surface that is not covered with resin). It is necessary to Therefore, in the present embodiment, the inner circumferential surface 41a of the core metal cylinder portion 41 is not covered with resin because it is locked to a movable mold during injection molding.

The resin cylinder part 53 of the cap body 50 has a large diameter part 55 that covers the core metal flange part 43 from the outside in the radial direction, and a small diameter part 57 that covers the metal core cylinder part 41 from the outside in the radial direction. The outer diameter of the large diameter portion 55 is larger than the inner diameter of the inner peripheral surface 2a of the inboard side end of the outer ring 2. Therefore, the large diameter portion 55 abuts the inboard side end of the outer ring 2 in the axial direction. Further, the outer diameter of the small diameter portion 57 is slightly larger than the inner diameter of the inner circumferential surface 2a of the inboard end of the outer ring 2. The small diameter portion 57 is press-fitted into the inner peripheral surface 2a of the inboard end of the outer ring 2. Therefore, it can be said that the small diameter portion 57 is a resin fitting portion of the cap 30.

Here, on the inner circumferential surface 53a of the resin cylindrical portion 53, a convex portion 59 that protrudes radially inward is provided at a portion closer to the inboard side than the core metal 40. That is, the convex portion 59 is provided on the inner circumferential surface of a portion of the large diameter portion 55 of the resin cylindrical portion 53 that is closer to the inboard side than the core bar 40 . The convex portion 59 may be provided over the entire circumference of the inner peripheral surface 53a of the resin cylinder portion 53, or may be provided intermittently. In any case, the convex portion 59 is formed by a recess provided in the movable mold on the radially inner side of the cap 30, and is engaged with the cap 30 when the injection-molded cap 30 is pulled out from the fixed mold on the radially outer side. It functions to maintain the stopped state.

1 and 2, the cross-sectional shape of the protrusion 59 is exaggerated by drawing it as a semicircle, but the actual height in the radial direction of the protrusion 59 is approximately 0.1 mm, and the width in the axial direction is is about 1 to 2 mm. Further, the cross-sectional shape of the convex portion 59 can be made into a substantially triangular shape with a lower slope than the top portion so that the injection-molded sensor holder can be easily removed from the movable mold using an ejector pin.

In the present embodiment, the inner peripheral surface 57a of the small diameter portion 57 of the resin cylindrical portion 53 on the outboard side than the core metal 40 is radially outer than the inner peripheral surface 41a of the core metal cylindrical portion 41. It is located so as to overlap with the outboard side end surface 41b of the cored metal cylinder portion 41. With this configuration, during injection molding, the outboard side end surface 41b of the cored metal tube 41 is used to stop the resin and prevent the resin from flowing out onto the inner peripheral surface 41a of the cored metal tube 41 (i.e., flashing). occurrence).

[Second embodiment]
FIG. 3 is an enlarged view of main parts of a hub unit bearing according to a second embodiment. In this embodiment, a convex portion 59 that protrudes radially inward is provided on the inner circumferential surface 53a of the resin cylinder portion 53 at a portion on the outboard side of the core metal 40. That is, the convex portion 59 is provided on the inner circumferential surface 57 a of the small diameter portion 57 of the resin cylinder portion 53 on the outboard side of the core bar 40 . Even with this configuration, when the injection-molded cap 30 is pulled out from the radially outer fixed mold, the convex portion 59 functions to maintain the state of being locked to the cap 30.

Also in this embodiment, the inner peripheral surface 57a of the small diameter portion 57 of the resin cylindrical portion 53 on the outboard side than the core metal 40 is radially outward than the inner peripheral surface 41a of the core metal cylindrical portion 41. It is located so as to overlap with the outboard side end surface 41b of the core metal cylinder portion 41. With this configuration, during injection molding, the outboard side end surface 41b of the cored metal tube 41 is used to stop the resin and prevent the resin from flowing out onto the inner peripheral surface 41a of the cored metal tube 41 (i.e., flashing). occurrence).

[Third embodiment]
FIG. 4 is an enlarged view of main parts of a hub unit bearing according to a third embodiment. In this embodiment, similarly to the second embodiment, a convex portion 59 that protrudes radially inward is provided on the inner circumferential surface 53a of the resin cylindrical portion 53 at a portion on the outboard side of the core metal 40. That is, the convex portion 59 is provided on the inner circumferential surface 57 a of the small diameter portion 57 of the resin cylinder portion 53 on the outboard side of the core bar 40 .

The inner peripheral surface 57a of the small diameter portion 57 of the resin cylindrical portion 53 on the outboard side of the core metal 40 has approximately the same diameter as the inner peripheral surface 41a of the core metal cylindrical portion 41. There is. Such a configuration can be adopted when it is allowed to some extent that the resin flows out onto the inner circumferential surface 41a of the core metal cylinder portion 41 (that is, the occurrence of flash) during injection molding.

[Fourth embodiment]
FIG. 5 is an enlarged view of a main part of a hub unit bearing according to a fourth embodiment. In this embodiment, as in the second and third embodiments, a convex portion 59 that protrudes radially inward is provided on the inner circumferential surface 53a of the resin cylindrical portion 53 at a portion on the outboard side of the core bar 40. provided. The convex portion 59 is provided over the entire width in the axial direction of the inner circumferential surface 57a of the small diameter portion 57 of the resin cylinder portion 53 on the outboard side of the core bar 40.

The inner circumferential surface 57a of the small diameter portion 57 of the resin cylindrical portion 53 on the outboard side of the core metal 40 (that is, the tip end surface of the convex portion 59) is closer to the inner circumferential surface 41a of the core metal cylindrical portion 41. It is also considered to have a small diameter. Such a configuration can be adopted when it is allowed to some extent that the resin flows out onto the inner circumferential surface 41a of the cored metal cylinder portion 41 (that is, the occurrence of flash) during injection molding.

[Fifth embodiment]
FIG. 6 is an enlarged view of a main part of a hub unit bearing according to a fifth embodiment. In this embodiment, the small diameter portion 57 of the resin cylindrical portion 53 covers a portion of the inner circumferential surface 41a of the core metal cylindrical portion 41 on the outboard side. Therefore, the inner circumferential surface 57a of the small diameter portion 57 of the resin cylindrical portion 53 has a smaller diameter than the inner circumferential surface 41a of the core metal cylindrical portion 41. As in the second to fourth embodiments, a convex portion 59 that protrudes radially inward is provided on the inner circumferential surface 53a of the resin cylinder portion 53 at a portion on the outboard side of the core bar 40. Such a configuration can be adopted when it is allowed to some extent that the resin flows out onto the inner circumferential surface 41a of the cored metal cylinder portion 41 (that is, the occurrence of flash) during injection molding.

Note that the present invention is not limited to the embodiments described above, and can be modified and improved as appropriate.

For example, in the embodiment described above, the insertion hole 54 for inserting the sensor was described as a through hole that penetrates the thick portion 52, but the insertion hole 54 may not penetrate through the thick portion 52.

Further, the cap 30 does not necessarily have to have a function of supporting the sensor, and the present invention is also suitable, for example, when it is desired to guarantee the axial position of the end surface of the cap 30.

1 Hub unit bearing 2 Outer ring 2a Inner circumferential surface 3 Inner ring 4 Rolling element 5 Seal ring 7 Stationary side flanges 8a, 8b Outer ring raceway surface 9 Hub ring 10 Inner ring member 11 Rotating side flange 11a Insertion holes 12a, 12b Inner ring raceway surface 13 Small diameter stage Part 14 Encoder 17 Hub bolt 18 Internal space 20 Large-diameter stepped portion 24 Clamping portion 26 Support ring 26a Annular portion 26b Flange portion 27 Encoder body 30 Cap 40 Core metal 41 Core metal cylindrical portion 41a Inner peripheral surface 41b Outboard side end surface 43 Core metal flange portion 50 Cap body 51 Resin bottom plate portion 52 Thick wall portion 53 Resin cylinder portion 53a Inner peripheral surface 54 Insertion hole 55 Large diameter portion 56 Insert nut 57 Small diameter portion 57a Inner peripheral surface 59 Convex portion

Claims (1)

an outer ring in which a double-row outer ring raceway surface is formed on the inner peripheral surface;
an inner ring having a double-row inner ring raceway surface formed on its outer circumferential surface;
a plurality of rolling elements rotatably disposed between the double-row inner ring raceway surface and the double-row outer ring raceway surface;
a cap fixed to an inboard side end of the outer ring and closing an opening on the inboard side of the outer ring;
A hub unit bearing comprising:
The cap has a synthetic resin cap body and a metal core fixed to the cap body,
The cap body has a cylindrical shape with a bottom as a whole, and includes a substantially disk-shaped resin bottom plate portion and a substantially cylindrical resin tube portion extending from a radially outer side of the resin bottom plate portion toward the outboard side. death,
The resin cylinder portion covers the core metal from the outside in the radial direction,
In the hub unit bearing, a convex portion protruding radially inward is provided on an inner circumferential surface of the resin cylindrical portion at a portion on an outboard side or an inboard side with respect to the core metal.

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